U.S. patent number 6,607,301 [Application Number 09/806,714] was granted by the patent office on 2003-08-19 for device and method for dark current noise temperature sensing in an imaging device.
This patent grant is currently assigned to Given Imaging Ltd.. Invention is credited to Arkady Glukhovsky, Gavriel J. Iddan, Gavriel Meron.
United States Patent |
6,607,301 |
Glukhovsky , et al. |
August 19, 2003 |
Device and method for dark current noise temperature sensing in an
imaging device
Abstract
A device, method and system for sensing the temperature of an
environment. An image sensor may be introduced into an environment
having an image sensing module. The dark current noise of the image
sensor may be sensed, and the temperature of the image sensor (and
environment) calculated. Such a device, system and method may be
used in, for example, a medical imaging device.
Inventors: |
Glukhovsky; Arkady (Nesher,
IL), Meron; Gavriel (Petach Tikva, IL),
Iddan; Gavriel J. (Haifa, IL) |
Assignee: |
Given Imaging Ltd. (Yoqneam,
IL)
|
Family
ID: |
11073108 |
Appl.
No.: |
09/806,714 |
Filed: |
October 9, 2001 |
PCT
Filed: |
August 03, 2000 |
PCT No.: |
PCT/IL00/00470 |
PCT
Pub. No.: |
WO01/10291 |
PCT
Pub. Date: |
February 15, 2001 |
Current U.S.
Class: |
374/175; 374/117;
374/121; 374/141; 374/E7.034; 600/109; 600/549 |
Current CPC
Class: |
A61B
1/041 (20130101); A61B 5/0008 (20130101); G01K
7/30 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); A61B 1/05 (20060101); G01K
7/30 (20060101); G01K 007/32 (); A61B 005/01 ();
A61B 001/04 () |
Field of
Search: |
;374/175,117,141,136,121,120,128 ;356/43,44
;600/474,549,101,109,117,118,127,153,160,562,573,104-106
;348/65,74-77,81-85,909 ;250/339.04,352 ;327/512 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2 353 166 |
|
Feb 2001 |
|
GB |
|
4109927 |
|
Apr 1992 |
|
JP |
|
5015515 |
|
Jan 1993 |
|
JP |
|
Other References
Jones, B.K., "Electrical Noise Thermometer," Appl. Phys. vol. 16,
No. 1, pp. 99-102 (May 1978).* .
The Radio Pill, Rowlands, et al., British Communications and
Electronics, Aug. 1960, pp. 598-601. .
Video Camera to "TAKE"--RF System lab, no date. .
Wellesley company sends body montiors into space--Crum, Apr. 1998.
.
Wireless transmission of a color television moving image from the
stomach using a miniature CCD camera, light source and microwave
transmitter. Swain CP, Gong F, Mills TN. Gastrointest Endosc
1997;45:AB40. .
CCD arrays cameras and displays, Holst G.C. p128, 2.sup.nd Edition,
Spie Press 1998 (no month). .
Photobit PB-159 DX Product Specification, Aug. 1998 (Version 3.0).
.
www.io.com--Random Electrical Noise: A Literature Survey, Research
Comments from Ciphers, Ritters, 1999 (Dec)..
|
Primary Examiner: Gutierrez; Diego
Assistant Examiner: Pruchnic, Jr.; Stanley J.
Attorney, Agent or Firm: Eitan, Pearl, Latzer & Cohen
Zedek, LLP.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of PCT patent application
PCT/IL00/00470, filed Aug. 4, 2000, titled "A METHOD FOR
TEMPERATURE SENSING", which was published in English, and which is
incorporated herein by reference in its entirety. PCT/IL00/00470
claims the benefit of Israeli Patent Application 131242, filed Aug.
4, 1999, entitled "A METHOD FOR TEMPERATURE SENSING", which is
incorporated herein by reference in its entirety.
Claims
What is claimed is:
1. A method for sensing the temperature of an environment
comprising the steps of: introducing into the environment an image
sensor having an image sensing module; sensing the dark current
noise of the image sensing module; calculating the temperature of
the image sensor from the sensed dark current noise; and
calculating the temperature of the environment from the calculated
image sensor temperature.
2. A method according to claim 1 further comprising the step of
displaying the calculated environment temperature.
3. A method according to claim 1 further comprising the step of
amplifying the sensed dark current noise prior to the step of
calculating the temperature of the image sensor.
4. A method according to claim 3 wherein the sensed dark current
noise is amplified by an integrating unit that is in communication
with the image sensor.
5. A method according to claim 1 wherein the step of sensing the
dark current noise of the image sensor is performed by an
integrating unit that is in communication with the image
sensor.
6. A method according to claim 5 wherein any one of the steps
subsequent to the step of sensing the dark current noise of the
image sensor is performed by a separate unit that is in
communication with the integrating unit.
7. A method according to claim 6 wherein the separate unit is
located outside of the environment.
8. A method according to claim 5 wherein the integrating unit is
located outside of the environment.
9. A method according to claim 1 wherein the steps of calculating
the temperature of the image sensor and calculating the temperature
of the environment are performed by an integrating unit that is in
communication with the image sensor.
10. A method according to claim 1 wherein the image sensor is
exposed to intermittent illuminated and dark periods.
11. A method according to claim 10 wherein the step of sensing the
dark current noise of the image sensor is performed during one or
more dark periods.
12. A method according to claim 1 wherein the image sensor is a
video camera.
13. A method according to claim 1 wherein the environment is a body
cavity.
14. The method according to claim 1, comprising obtaining visual
data.
15. A system for sensing the temperature of an environment
comprising an image sensor in communication with an integrating
unit, said image sensor being introduced into an environment; and
said integrating unit receiving dark current noise from the image
sensor, calculating the temperature of the image sensor, and
calculating the temperature of the environment.
16. A system according to claim 15 wherein the integrating unit
amplifies the received dark current noise prior to calculating the
temperature of the image sensor, and calculating the temperature of
the environment.
17. A system according to claim 16 wherein one or more of the steps
of amplifying the received dark current noise, calculating the
temperature of the image sensor and calculating the temperature of
the environment are performed by a separate unit that is in
communication with the integrating unit.
18. A system according to claim 17 wherein the separate unit is
located outside of the environment.
19. A system according to claim 15 wherein one or both of
calculating the temperature of the image sensor and calculating the
temperature of the environment are performed by a separate unit
that is in communication with the integrating unit.
20. A system according to claim 19 wherein the separate unit is
located outside of the environment.
21. A system according to claim 15 wherein the integrating unit
further displays the calculated environment temperature.
22. A system according to claim 21 wherein displaying the
calculated environment temperature is performed by a separate unit
that is in communication with the integrating unit.
23. A system according to claim 22 wherein the separate unit is
located outside of the environment.
24. A system according to claim 15 wherein the integrating unit is
located outside of the environment.
25. A system according to claim 15 wherein the image sensor is
exposed to intermittent illuminated and dark periods.
26. A system according to claim 25 further comprising a switch
which is in communication with an illumination indicator for
receiving indication of illumination, said switch enabling
communication between the image sensor and integrating unit only
during one or more dark periods.
27. A system according to claim 26 wherein the switch is capable of
accepting signals from an external operator.
28. A system according to claim 15 further comprising a switch
which controls illumination elements for exposing the image sensor
to intermittent illuminated and dark periods, said switch enabling
communication between the image sensor and integrating unit only
during one or more dark periods.
29. A system according to claim 28 wherein the switch is capable of
accepting signals from an external operator.
30. A system according to claim 15 wherein the integrating unit is
in communication with functional units for operating said
functional units in accordance with a predetermined
temperature.
31. A medical device comprising the system according to claim
30.
32. A medical device according to claim 31 in which the functional
units are units that enable the collection of samples from the
environment.
33. A system according to claim 15 wherein the image sensor is a
video camera.
34. A system according to claim 15 wherein the environment is a
body cavity.
35. A medical device comprising the system according to claim
15.
36. A medical device according to claim 35 wherein the device is a
swallowable autonomous endoscope.
37. The system according to claim 15, wherein said image sensor is
capable of obtaining visual data.
Description
FIELD OF THE INVENTION
The present invention relates to a method and system for measuring
the temperature of an environment, such as the interior of the
body.
BACKGROUND OF THE INVENTION
In many circumstances it is important to measure the temperature
inside a material body. Such circumstances may occur during
industrial processes or exploration and analysis processes, such as
in geophysical probing or in medical diagnostics and treatment of
internal parts of the body.
Conventional thermometry and absolute thermometry are known methods
for measuring temperature.
Conventional thermometry is based upon the temperature coefficient
of properties of materials, such as resistance or mechanical
expansion.
Absolute thermometry is a method which directly measures thermal
energy of a sensor resistance. This method is based upon the known
physical phenomenon of spontaneous thermal noise arising from the
Brownian motion of ionized molecules within a resistance.
Thermal noise, which can be discussed in terms of thermal current,
provides a direct measurement of temperature on a thermodynamic
scale, thus the Boltzmann constant defines the temperature. The
phenomenon of thermal noise is derived, for example, in the book:
CCD arrays cameras and displays by Hoist G. C., p. 128, 2.sup.nd
edition, SPIE Press, 1998. The formula used to define thermal
current is:
where k is the Boltzmann constant, T is the temperature of a
sensor, and C is the capacitance of the sensor. Thus the magnitude
of the signals produced by the thermal current is directly
proportional to the square root of the temperature of the sensor.
Experiments have indicated that the signal doubles with the
increase of 7.degree. C. (degrees Centigrade), which means that a
resolution better than 0.1.degree. C. is achieved.
In image sensors, the thermal current produced in an operating
photodetector device, when no optical radiation impinges on the
detector, is called "dark current". In CCD cameras dark current is
basically charge which accumulates in the CCD pixels due to thermal
noise. The effect of dark current is to produce an additive
quantity to the electron count in each pixel.
U.S. Pat. No. 3,937,086 to von Thuna, U.S. Pat. No. 5,354,130 to
Seppa et al. and U.S. Pat. No. 5,098,197 to Shepard et al. all
describe devices for measuring the absolute temperature of a body
material by receiving and analyzing the thermal noise of the body
material.
U.S. Pat. No. 4,246,784 to Bowen describes a method for noninvasive
temperature measurement of the interior of a body using the
acoustic thermal noise spectrum of the measured body.
None of these temperature measurement methods utilize an image
sensor to measure the thermal noise of a body material.
SUMMARY OF THE INVENTION
The present invention provides a method and system for sensing the
temperature of an environment, such as inside a body, by
calculating the temperature of an image sensor in the environment
and deducing the environment's temperature from the image sensor's
calculated temperature. The temperature of the image sensor is
calculated by measuring its generated dark current noise.
The method and system of the present invention have the advantage
of utilizing an image sensor, in which thermal noise is easily
detectable, for deducing the temperature of a material body.
Furthermore, according to the invention, a single sensor is
utilized for obtaining visual data and data relating to the
temperature of the environment. Thus, diverse information about an
environment can be obtained utilizing a single sensing device.
There is thus provided according to the present invention a method
for sensing the temperature of an environment comprising the steps
of introducing into an environment an image sensor having an image
sensing module, sensing the dark current noise of the image sensor,
calculating the temperature of the image sensor, calculating the
temperature of the environment and optionally displaying the
calculated environment temperature.
It will be appreciated that the term "environment" in the present
invention relates to a space enclosed within walls in which it is
desired to measure the temperature of the space and/or of the
walls.
The temperature of the image sensor is indicative of the
temperature of it's immediate surroundings and, relying on known
factors such as heat distribution, distance from the image sensor,
etc., the temperature of further areas can also be calculated.
The image sensors utilized in the invention can be digital cameras
or video cameras such as vidiocon, CCD cameras or CMOS cameras.
The present invention further provides a system for sensing the
temperature of an environment. The system comprises an image sensor
having an image sensing module in communication with an integrating
unit for detecting the dark current of the image sensor image
sensing module and for calculating the temperature of the image
sensor. The integrating unit may further calculate the temperature
of the environment or the temperature of the environment may be
calculated, based on data from the integrating unit, by a separate
unit that is in communication with the integrating unit
The integrating unit may have an amplifying function for amplifying
signals received from the image sensor.
The communication between the image sensor and integrating unit can
be optionally controlled according to the illumination conditions,
optionally through a switch which enables communication only during
periods in which the sensor is not illuminated.
BRIEF DESCRIPTION OF THE FIGURES
The present invention will be understood and appreciated more fully
from the following detailed description taken in conjunction with
the figures in which:
FIG. 1 is a block diagram representing an embodiment of the method
according to the invention;
FIG. 2 is a schematic illustration of an embodiment of the system
according to the invention;
FIG. 3 is a schematic illustration of a functional block layout of
the image sensor according to the invention; and
FIG. 4 is a schematic illustration of a medical device comprising
the system according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Analytical and diagnostic processes which utilize image sensors to
monitor environments could benefit from obtaining information
relating to the temperature of the environment, as a local change
of temperature can indicate an irregular event.
For example, U.S. Pat. No. 5,604,531, which is assigned to the
common assignees of the present application, describes a
swallowable capsule that can pass through the entire digestive
tract and operate as an autonomous video endoscope U.S. Pat. No.
5,604,531, is hereby incorporated by reference. The swallowable
capsule includes a) a camera system, b) an optical system for
imaging an area of interest onto the camera system and c) a
transmitter which transmits the video output of the camera system.
Visual data obtained by the swallowable capsule can indicate, inter
alia, the location of pathologies in the gastrointestinal tract.
Also a local change of temperature in the gastrointestinal tract
can be indicative of a pathology. Thus, the information obtained by
visual means can be complemented and focused by information
relating to local temperature in the gastrointestinal tract.
The method of the present invention enables contemporary visual
monitoring and temperature sensing.
The method is schematically described by a block diagram shown in
FIG. 1. An image sensor, such as in the above mentioned swallowable
capsule, is inserted 10 into an environment, such as the
gastrointestinal tract.
Illumination is provided intermittently, either by elements
connected to the image sensor itself or by external sources. When
illumination is provided 12 only visual data is obtained 14 and
displayed 16. A process for obtaining and displaying visual data is
described, for example, in the above mentioned U.S. Pat. No.
5,604,531.
In an intermittent dark period 11 an integrating unit 100 is
activated to obtain dark current data 13 from the image sensor,
though it is not imperative to shut off illumination in order to
obtain data relating to dark current noise, as will be discussed in
more detail below.
The integrating unit 100 is a processor capable of amplifying the
obtained data 15, if necessary, and calculating the image sensor
temperature 17 using the known equations derived for thermal noise.
It will be appreciated that these equations are an approximation of
a complex phenomenon and that calibration should be employed in
order to deduce the actual calculations that will be applied.
The environment temperature is then calculated 19, either by the
integrating unit 100 or by a separate unit in communication with
the integrating unit 100. Calculations of the environment
temperature are based on the existence of thermal equilibrium
between the image sensor and environment. These calculations take
into account energy dissipation from the image sensor. Local
temperature or the average temperature within the environment may
be calculated, depending on specific requirements. The calculated
temperature may then be displayed 18.
It will be appreciated that the various calculations are carried
out by software or software means executable on computing means
such as a computer or similar data processors, microprocessors,
embedded processors, microcomputers, microcontrollers etc.,
The integrating unit 100 may comprise separate processors, which
need not all be physically connected. Some of the functions carried
out by integrating unit 100, such as calculating the image sensor
temperature 17 and calculating the environment temperature 19, can
be carried out in processors that are external to the environment
and that are fed with data from the integrating unit 100 by
communication such as by IR or radio. Indeed, if an operator is to
note the temperature of the environment, at least the function of
displaying the calculated temperature 18 must be performed
externally to the environment.
Integrating unit 100 may be in communication with other units to
further process and use the data obtained by it. For example, a
swallowable capsule, such as described in U.S. Pat. No. 5,604,531,
may comprise a sample chamber for collecting samples from the
environment of the digestive tract. The process of collecting a
sample can be controlled by integrating unit 100, such that samples
are collected only in locations along the digestive tract in which
a predetermined temperature is prevalent.
Reference is now made to FIG. 2 which is a schematic illustration
of the system according to an embodiment of the invention. The
system comprises an image sensor 20 having an image sensing module
which includes a pixel array (as demonstrated in FIG. 3) in
communication with an integrating unit 22. Communication is enabled
by temperature sense switch 24 which is controlled by illumination
indicator 26, such that communication is enabled only during dark
periods.
When communication between the image sensor 20 and integrating unit
22 is established, integrating unit 22 receives dark current data
from image sensor 20.
As will be discussed below, it is possible to calculate the image
sensor's 20 temperature based on dark current data obtained from a
single pixel of the image sensor pixel array, though data obtained
from a higher number of pixels will achieve more accurate results.
It is therefore possible to keep a portion of the image sensor's 20
pixels of the pixel array, constantly unexposed to illumination,
and obtain dark current data from the unexposed pixels, without
having to shut off the illumination.
Thus, dark current data can be obtained also during constant
illumination by either covering a portion of the pixels of the
pixel array or by having a portion of the pixel array pixels
outside of the image field, e.g. the pixels in the periphery of the
pixel array.
The integrating unit 22 is a processor capable of amplifying the
dark current signal and calculating the image sensor temperature
from the dark current signal. It is further capable of calculating
the environment temperature from the image sensor temperature and
is capable of displaying the calculated environment temperature 21.
Integrating unit 22 may control different temperature sensitive
units 28, such as the sample chamber described above, in
correspondence with predetermined temperatures.
Reference is now made to FIG. 3 which is a schematic illustration
of a functional block layout of the image sensor according to the
invention. The image sensor comprises a single chip 40 having an
image sensing module 42 and a control circuits area 44. The image
sensing module 42 includes a pixel array 48 for capturing an image.
The control circuits area 44 includes the timing and logic
circuitry 47 and A/D circuitry 46.
Signals can be received from all the pixels of the pixel array 48.
Dark current is received from pixels that are not illuminated or
from pixels during a dark period whereas current signals received
from an illuminated pixel are the summation of the dark current and
light current of the pixel. The accumulation of signals from all
the pixels is converted to data which is communicated through a
transmitter to the integrating unit for decoding and for displaying
a visual representation and/or the temperature derived from the
data.
The system of the invention will be further described and
demonstrated by FIG. 4 which is a schematic illustration of a
medical device comprising a system according to the invention.
The medical device illustrated in FIG. 4 is a swallowable capsule,
generally referenced 30, such as that described in the above
mentioned U.S. Pat. No. 5,604,531. Swallowable capsule 30 comprises
a CMOS camera 32, that is in communication with integrating unit
34. The swallowable capsule 30 further comprises illuminating
elements 36 that are in communication with illumination indicator
33. The gastrointestinal tract walls 31 are illuminated by
illuminating elements 36, in intermittent pulses, capturing
consecutive images of the gastrointestinal tract walls 31 by camera
32, enabling an operator to view the gastrointestinal tract walls.
Communication between camera 32 and integrating unit 34 is enabled
in between illumination pulses when illumination indicator 33,
sensing the lack of illumination, activates the temperature sense
switch (not shown) to an ON position.
Alternatively, the illumination indicator 33 may be activated by
the operator to simultaneously turn off the illumination elements
36 and switch the temperature sense switch to an ON position.
Once communication is established between camera 32 and integrating
unit 34 dark current signals generated from camera 32 are received
and processed, as described above, by integrating unit 34. The
calculated gastrointestinal temperature is displayed on a display
unit external to the gastrointestinal tract.
Swallowable capsule 30 further comprises a sample chamber 35 for
collecting samples from the gastrointestinal tract environment. The
collected sample may be cells from the gastrointestinal tract walls
or a liquid sample from the gastrointestinal tract environment. The
mechanism for collecting samples, which can be any suitable
mechanism known in the art, is controlled by integrating unit 34,
such that it is activated in accordance with the gastrointestinal
tract environment calculated temperature. Alternatively, the
mechanism can be controlled by the operator based on the displayed
temperature.
It will be appreciated by persons skilled in the art that the
present invention is not limited to what has been particularly
shown and described hereinabove. Rather the scope of the present
invention is defined only by the claims which follows.
* * * * *
References